The present invention relates to an apparatus for sorting individual timber pieces of different dimensions and/or qualities into a number of mutually superposed sorting compartments, and comprising a conveyor for vertical transport along the infeed ends of the sorting compartments of individual timber pieces with their longitudinal direction approximately horizontal and transversely directed in relation to the longitudinal direction of the sorting compartments, and a transfer device for transferring a specific timber piece from the conveyor to a specific sorting compartment.
Apparatuses of the type intimated by way of introduction are previously known in the art. The individual sorting compartments are represented by approximately horizontal conveyors of considerable length, of the order of magnitude of 50-100 m or possibly more. These conveyors are superposed on one another with a spacing of approximately 30-40 cm. The number of sorting compartments in the vertical direction may be large, often as many as 30-50 in number.
Along the infeed ends of the sorting compartments, a conveyor runs which transports the individual timber pieces up to a certain, predetermined sorting compartment where the timber piece is discharged by means of a transfer device and is fed into the selected sorting compartments. The individual timber pieces may arrive in random sequence as regards dimensions and qualities, but are identified and registered by a computer which controls the transfer devices so that the timber pieces are fed to the correct sorting compartment. The conveyor which runs in conjunction with the infeed ends of the sorting compartments moves continuously.
The transfer devices have hitherto been placed in the downwardly moving conveyor which is in conjunction with the infeed ends of the sorting compartments. This implies that, when a transfer device is activated, it must extend through the path which the individual timber pieces described on the downwardly moving conveyor. This entails that a transfer device must be activated, transfer its timber piece to the associated sorting compartment and thereafter return to the starting position outside the path of movement of the timber pieces before a new timber piece may pass. Such a work cycle takes considerable time, and so capacity will not be that intended.
It has thus been the work rate of the transfer devices which has hitherto limited the overall capacity of the plant. As a result, it has not been possible to carry out such working operations as sawing, normal mechanised transport within the plant, cutting-to-length, etc., at maximum speed, for which reason the plant as a whole has too low capacity.
In order to attempt to increase the capacity of the plant, the time available for each working cycle in the transfer devices has been increased. This has been achieved by an increase of the linear transport length for each timber piece on the downwardly moving conveyor from the uppermost sorting compartment to the lowermost. In order to achieve this, the downwardly moving conveyor has been inclined in that the individual sorting compartments do not begin in a vertical plane but in a plane which inclines to the vertical. This has been realised in that an upper sorting compartment extends out beyond a subjacent sorting compartment. Given that the downwardly moving conveyor follows this pattern and, hence, in principle maintains constant distance to the mouths of the sorting compartments, the linear transport length in the downwardly moving conveyor will be longer than would have been the case if the sorting compartments had been arranged with their infeed ends in a vertical plane.
The above-described oblique inclination of the infeed ends of the sorting compartments entails that the lowermost, and hence the shortest, sorting compartment will be dimensioned for the entire plant, for which reason extra costs are incurred for the unnecessarily long upper sorting compartments.
Furthermore, despite the oblique inclination of the conveyor, it has not been possible to achieve the work rate for the plant which is desirable.
The present invention has for its object to design the apparatus intimated by way of introduction such that the drawbacks inherent in prior art technologies are obviated. In particular, the present invention has for its object to design the apparatus according to the present invention so that its capacity is greatly improved as compared with prior art technology. Further, the present invention has for its object to obviate the need for unnecessarily long sorting compartments.
The objects forming the basis of the present invention will be attained if the apparatus intimated by way of introduction is characterised in that the transfer device has at least one transfer member per sorting compartment, and that each transfer member is movable between a passive position outside the path of the conveyor and in conjunction with the infeed end of the sorting compartment, and an active position within the path of the conveyor for engagement with a timber piece carried by the conveyor and transferring it to the sorting compartment.